水泵水轮机预开导叶的优化分析

Optimization of misaligned guide vanes scheme of pump-turbine

水泵水轮机在S特性区内运行时将发生机组并网困难或者在甩负荷过程中水压异常上升的问题,使机组震动加剧.目前解决S特性的有效方法为预开导叶,即在小开度下预开启偶数个导叶至指定开度来缓解S特性区的不稳定性.为了探究有效的预开导叶方式,首先分别根据预开导叶的数目及位置的不同,设计4种预开导叶方案,通过全三维流道的数值模拟分析找到能够缓解S特性的最优方案;其次对选定的最优方案进行模型试验并与模拟结果进行对比验证.结果表明:并不是预开的导叶数越多,改善S特性越好;等间隔分布预开导叶改善S特性的效果要优于集中分布的预开导叶方案;最终得出在预开2#,7#,12#,17#2对导叶的情况下对水泵水轮机S特性缓解效果最为明显.计算结果与模型试验的对比表明了模拟结果与试验结果趋于一致.

Pump-turbine operation along the S-shaped curve may encounter difficulties in loading re- jection process or unusual increases of water pressure resulted in violent machine vibrations. The pre- vailing and effective solution to this problem is misaligned guide vanes （MGV） technique, that is, to control the stability of the machine operation in the S region by pre-opening several guide vanes （us- ually an even number） to specified angles. In order to explore the feasible and effective way of pre-o- pening guide vanes, firstly, based on the numbers and the locations of MGVs, four MGVs were de- signed, in the hope of finding the most optimal solution to eliminate S characteristics through fully three-dimensional numerical simulation of flow analysis; secondly, model tests for the selected most optimal program were performed and the experimental results and simulation results were compared. The analysis of the results of the four pre-opening programs shows that more number of pre-opening guide vanes does not necessarily mean better improvement of S characteristics and equally-distributed guide vanes is better than centrally-distributed ones in improving S characteristics. It is concluded that the program of pre-opening 2#,7#, 12#, 17# two-pair characteristics of pump-turbine; CFD calculations and simulation is well consistent with experimental data. guide vanes can most effectively mitigate the S the comparison with model test show that CFD